Existing probe monitors that measure power density require batteries or power supplies, are expensive, and are easily damaged by inadvertent exposure to the extremely high fields that are present in close proximity to high gain/high power transmitting antennas. Personnel safety in the presence of high intensity electromagnetic fields is jeopardized by the propensity of such monitors to be easily damaged. A simple to use and inexpensive monitor that is highly reliable in the presence of high intensity fields is needed to provide accurate warning when safe field levels are exceeded. The time varying magnetic field safety probe quickly and accurately determines the safety of a work area against this hazard.